Linus,
Please pull from the 'linus' branch of
git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm.git
To get a one-liner fixing a host oops running non-pae guests.
Avi Kivity (1):
KVM: Fix off-by-one when writing to a nonpae guest pde
---
drivers/kvm/mmu.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
commit 6b8d0f9b180cb93513bb65f705b299370f0357a1
Author: Avi Kivity <[email protected]>
Date: Wed Apr 18 11:18:18 2007 +0300
KVM: Fix off-by-one when writing to a nonpae guest pde
Nonpae guest pdes are shadowed by two pae ptes, so we double the offset
twice: once to account for the pte size difference, and once because we
need to shadow pdes for a single guest pde.
But when writing to the upper guest pde we also need to truncate the
lower bits, otherwise the multiply shifts these bits into the pde index
and causes an access to the wrong shadow pde. If we're at the end of the
page (accessing the very last guest pde) we can even overflow into the
next host page and oops.
Signed-off-by: Avi Kivity <[email protected]>
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index e85b4c7..cab26f3 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -1171,6 +1171,7 @@ void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
* and zap two pdes instead of one.
*/
if (level == PT32_ROOT_LEVEL) {
+ page_offset &= ~7; /* kill rounding error */
page_offset <<= 1;
npte = 2;
}
-
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